Cold, Hard Facts

IN the debate on global warming, the data on the climate of Antarctica has been distorted, at different times, by both sides. As a polar researcher caught in the middle, I’d like to set the record straight.

In January 2002, a research paper about Antarctic temperatures, of which I was the lead author, appeared in the journal Nature. At the time, the Antarctic Peninsula was warming, and many people assumed that meant the climate on the entire continent was heating up, as the Arctic was. But the Antarctic Peninsula represents only about 15 percent of the continent’s land mass, so it could not tell the whole story of Antarctic climate. Our paper made the continental picture more clear.

My research colleagues and I found that from 1986 to 2000, one small, ice-free area of the Antarctic mainland had actually cooled. Our report also analyzed temperatures for the mainland in such a way as to remove the influence of the peninsula warming and found that, from 1966 to 2000, more of the continent had cooled than had warmed. Our summary statement pointed out how the cooling trend posed challenges to models of Antarctic climate and ecosystem change.

Newspaper and television reports focused on this part of the paper. And many news and opinion writers linked our study with another bit of polar research published that month, in Science, showing that part of Antarctica’s ice sheet had been thickening — and erroneously concluded that the earth was not warming at all. “Scientific findings run counter to theory of global warming,” said a headline on an editorial in The San Diego Union-Tribune. One conservative commentator wrote, “It’s ironic that two studies suggesting that a new Ice Age may be under way may end the global warming debate.”

In a rebuttal in The Providence Journal, in Rhode Island, the lead author of the Science paper and I explained that our studies offered no evidence that the earth was cooling. But the misinterpretation had already become legend, and in the four and half years since, it has only grown.

Our results have been misused as “evidence” against global warming by Michael Crichton in his novel “State of Fear” and by Ann Coulter in her latest book, “Godless: The Church of Liberalism.” Search my name on the Web, and you will find pages of links to everything from climate discussion groups to Senate policy committee documents — all citing my 2002 study as reason to doubt that the earth is warming. One recent Web column even put words in my mouth. I have never said that “the unexpected colder climate in Antarctica may possibly be signaling a lessening of the current global warming cycle.” I have never thought such a thing either.

Our study did find that 58 percent of Antarctica cooled from 1966 to 2000. But during that period, the rest of the continent was warming. And climate models created since our paper was published have suggested a link between the lack of significant warming in Antarctica and the ozone hole over that continent. These models, conspicuously missing from the warming-skeptic literature, suggest that as the ozone hole heals — thanks to worldwide bans on ozone-destroying chemicals — all of Antarctica is likely to warm with the rest of the planet. An inconvenient truth?

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Also missing from the skeptics’ arguments is the debate over our conclusions. Another group of researchers who took a different approach found no clear cooling trend in Antarctica. We still stand by our results for the period we analyzed, but unbiased reporting would acknowledge differences of scientific opinion.

The disappointing thing is that we are even debating the direction of climate change on this globally important continent. And it may not end until we have more weather stations on Antarctica and longer-term data that demonstrate a clear trend.

In the meantime, I would like to remove my name from the list of scientists who dispute global warming. I know my coauthors would as well.

Corrections:An Op-Ed article on Thursday, about the use of climate studies, included an incorrect date. A study found that part of Antarctica cooled from 1986 to 2000, not 1996 to 2000.

An Op-Ed article on July 27, about the use of climate studies, incorrectly described a San Diego Union-Tribune article that questioned global warming. It was a column written by an editorial-board member, not an editorial.

Correction: July 29, 2006

An Op-Ed article on Thursday, about the use of climate studies, included an incorrect date. A study found that part of Antarctica cooled from 1986 to 2000, not 1996 to 2000.

Correction: August 4, 2006

An Op-Ed article on Monday, about presidential signing statements, misidentified the president whose right to fire postmasters was upheld by the Supreme Court. It was Woodrow Wilson, not Calvin Coolidge.

 An Op-Ed article on July 27, about the use of climate studies, incorrectly described a San Diego Union-Tribune article that questioned global warming. It was a column written by an editorial-board member, not an editorial.

Peter Doran is an associate professor of earth and environmental sciences at the University of Illinois at Chicago.

A version of this op-ed appears in print on , on Page A25 of the New York edition with the headline: Cold, Hard Facts. Today's Paper|Subscribe